To extend the information here slightly - UK "debit cards" generally operate differently underneath to their US cousins and merchants that "can't do debit cards / can only do credit cards" do not (in my experience) actually run in to the same problems for UK-issued cards as they might with US-issuers.
I have had zero problems using my UK-issued Visa-Debit type card (aka "normal bank card", in UK terms) to return to Premium and buy L$ on the Lindex, literally in the last week.